Night Terrors

Go in the cave behind the quest giver, it continues to the right after you enter. It's easy to miss since this cave looks like one of the standard "dead end" ones.

From there you will see Uchek, whom you will speak to in order to continue the quest. Once you do, you will phase into a spirit world, where the objective is to find the three "shrines". There is one in the left and right wing from Uchek, and one more directly behind him in the middle. Simply walk up to a campfire to cleanse that shrine.

You will be aggro'd by various spirits in the cave, and while you cannot directly attack them, you can kill them with the Light of Souls item in your bags. It does an AOE blast around your character killing any souls attacking you. They don't hit very hard, so I gather up a few, training them together while I head to the shrines, and then click the Light of Souls on cooldown to kill a bunch at once.

Once all three camps are purged, you exit the spirit realm. Then leave the cave, and talk to Buunu once more to turn in.

1st: Go right of quest giver along a ledge to the end.
2nd: Around the centre on the minimap
3rd: Take a left in the small 'nook' on the bottom of the map

If you're anything like me, you'll be standing by the campfire wondering if the quest is bugged, but the first campfire right by uchek is not a shrine